Human growth hormone (hGH) is secreted in the human pituitary. In its mature form it consists of 191 amino acids, has molecular weight of about 22,000, and thus is more than three times as large as insulin. This hormone is a linear polypeptide containing two intrachain disulfide bridges. Until the advent of recombinant DNA technology, hGH could be obtained only by laborious extraction from a limited source--the pituitary glands of human cadavers. The consequent scarcity of the substance limited its application to treatment of hypopituitary dwarfism even though it has been proposed to be effective in the treatment of burns, wound healing, dystrophy, bone knitting, diffuse gastric bleeding and pseudarthrosis. hGH can be produced in a recombinant host cell, in quantities which would be adequate to treat hypopituitary dwarfism and the other conditions for which it is effective. See, for example, U.S. Pat. No. 4,342,832.
The major biological effect of hGH is to promote growth. The organ systems affected include the skeleton, connective tissue, muscles, and viscera such as liver, intestine, and kidneys. Growth hormone exerts its action through interaction with specific receptors on cell membranes.
Human growth hormone has been formulated in a variety of ways as shown in Table I.
TABLE I __________________________________________________________________________ Molar Molar hGH Mannitol Ratio if Glycine Ratio if Buffer pH (of (mg/ml upon (mg/ml upon hGH = (mg/ml upon hGH = (mg/ml upon reconstituted reconstitution) reconstitution) 1 reconstitution) 1 reconstitution) solution) __________________________________________________________________________ Genentech Protropin 1.0 r-met hGH 8.0 (960) 0 (0) 0.83 sodium 7.8 (5 mg per vial) phosphate Genentech Clinical 1.0 r-hGH 0 (0) 18.9 (5340) 1.8 Dibasic 7.4 rhGH formulation sodium (5 mg per vial (IND)) phosphate (2 mg per vial (NDA)) dodecahydrate Lilly met-HGH 1.0 r-met hGH 3.5 (428) 1.0 (294) 0.227 Na.sub.2 HPO.sub.4 7.2 (2 mg per vial) Lilly r-HGH 1.0 rhGH 5.0 (611) 1.0 (294) 0.227 Na.sub.2 HPO.sub.4 7.2 (2 mg per vial) Kabivitrum Crescormon 2.0 I.U. pit. hGH 0 (0) 20.0 (ca. 5860) 0.5 sodium 7.4 (4 I.U. per vial) (ca. 1 mg) phosphate Serono Pituitary hGH 2.0 I.U. pit. hGH 20.0 (ca. 0 ? sodium (2 and 10 I.U. per vial) (ca. 1 mg) 2415) phosphate __________________________________________________________________________
In order that materials like hGH be provided to health care personnel and patients, these materials must be prepared as pharmaceutical compositions. Such compositions must maintain activity for appropriate periods of time, must be acceptable in their own right for easy and rapid administration to humans, and must be readily manufacturable. In many cases pharmaceutical formulations are provided in frozen or in lyophilized form. In this case, the composition must be thawed or reconstituted prior to use. The frozen or lyophilized form is often used to maintain biochemical integrity and the bioactivity of the medicinal agent contained in the compositions under a wide variety of storage conditions, as it is recognized by those skilled in the art that lyophilized preparations often maintain activity better than their liquid counterparts. Such lyophilized preparations are reconstituted prior to use by the addition of suitable pharmaceutically acceptable diluent(s), such as sterile water for injection or sterile physiological saline solution, and the like.
Alternatively, the composition can be provided in liquid form appropriate for immediate use. Desirable is a liquid formulation which maintains its activity in long term storage.
Current formulations of hGH lose activity due to formation of dimer and higher order aggregates (macro range) during formulation processing as well as during storage and reconstitution. Other chemical changes, such as deamidation and oxidation may also occur upon storage.
Prior attempts to stabilize hGH have not fully succeeded in preventing dimer formation. The problems associated with dimer being present are noted in Becker, G.W., Biotechnolozv and Aoolied Biochemistry 9, 478 (1987).
It is an object of the present invention to prepare stable, aggregate-free formulations of human growth hormone.
A further object of the invention is to provide a formulation which can be aerosolized for pulmonary use, or used in a needleless jet injector for subcutaneous injection.
A further object of the invention is to provide an hGH formulation with enhanced characteristics.
A still further object of the invention is to provide an hGH formulation wherein no component is derived from animals e.g. natural albumin, thus avoiding possible contamination of the formulation with impurities.
Other objects, features and characteristics of the present invention will become more apparent upon consideration of the following description and the appended claims.